Electronic structure and relaxation dynamics in a superconducting topological material

Madhab Neupane, Yukiaki Ishida, Raman Sankar, Jian Xin Zhu, Daniel S. Sanchez, Ilya Belopolski, Su Yang Xu, Nasser Alidoust, M. Mofazzel Hosen, Shik Shin, Fangcheng Chou, M. Zahid Hasan, Tomasz Durakiewicz

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Abstract

Topological superconductors host new states of quantum matter which show a pairing gap in the bulk and gapless surface states providing a platform to realize Majorana fermions. Recently, alkaline-earth metal Sr intercalated Bi 2 Se 3 has been reported to show superconductivity with a T c ∼ 3 K and a large shielding fraction. Here we report systematic normal state electronic structure studies of Sr 0.06 Bi 2 Se 3 (T c ∼ 2.5 K) by performing photoemission spectroscopy. Using angle-resolved photoemission spectroscopy (ARPES), we observe a quantum well confined two-dimensional (2D) state coexisting with a topological surface state in Sr 0.06 Bi 2 Se 3. Furthermore, our time-resolved ARPES reveals the relaxation dynamics showing different decay mechanism between the excited topological surface states and the two-dimensional states. Our experimental observation is understood by considering the intra-band scattering for topological surface states and an additional electron phonon scattering for the 2D states, which is responsible for the superconductivity. Our first-principles calculations agree with the more effective scattering and a shorter lifetime of the 2D states. Our results will be helpful in understanding low temperature superconducting states of these topological materials.

Original languageEnglish (US)
Article number22557
JournalScientific reports
Volume6
DOIs
StatePublished - Mar 3 2016

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    Neupane, M., Ishida, Y., Sankar, R., Zhu, J. X., Sanchez, D. S., Belopolski, I., Xu, S. Y., Alidoust, N., Hosen, M. M., Shin, S., Chou, F., Hasan, M. Z., & Durakiewicz, T. (2016). Electronic structure and relaxation dynamics in a superconducting topological material. Scientific reports, 6, [22557]. https://doi.org/10.1038/srep22557